Control circuit useful with sewing machines



1967 R. c. BRANDRIFF ETAL 3,352,257

CONTROL CIRCUIT USEFUL WITH SEWING MACHINES Filed Nov. 29, 1965 2Sheets-Sheet l Robert C. Brandriff Charles G. Pickeff WITNESS ATTORNEYNov. 14, 1967 RC. BRANDRIFF ETAL 3,352,267

CONTROL CIRCUIT USEFUL WITH SEWING MACHINES 2 Sheets-Sheet 2 Filed Nov.29, 1965 ubE mwqaa QwEwwn f B m Y od m E THC N mm M V T N T s I 8 mm r/0h 5% Y B WITNESS United States Patent 3,352,267 CONTROL CIRCUIT USEFULWITH SEWING MACHINES Robert C. Brandritf, Williamstown, and Charles G.Pickett, Dover, N.J., assignors to The Singer Company, New York, N.Y., acorporation of New Jersey Filed Nov. 29, 1965, Ser. No. 510,227 11Claims. (Cl. 112-218) This invention relates in general to controlcircuits and in particular to circuits for use in so controlling themodulation of a pulse train that the time duration and the spacing ofpulses therein are both substantially equal in time to the samereference time period. In a presently preferred environment for theinvention, the circuit is employed to monitor the rate of threadconsumption of an industrial sewing machine, whereby when such rate iseither too low or too high, an alarm or other control unit is excited.The circuit of the invention, While being broadly a special arrangementof Boolean logic elements which as is known may take a variety offorms," e.g. electrical, magnetic, etc., nevertheless here preferablyemploys an arrangement of turbulence-type fluid logic switchingcomponents (although Coanda-type components may readily be adapted foruse with'the invention).

In more detail, the circuit of the invention is adapted to receive apulse train wherein the durations of the pulses therein and theirspacings are necessarily substantially equal in time to each other, andwherein the time-lengths of such durations and spacings arecontrollable. When the pulse durations and spacings are substantiallyequal in time to a reference time period, the output of the instantcontrol circuit is made to be zero; when such durations and spacings aregreater or less in length of time than the reference time period, thecircuit is made to produce an output the time integral of which is asignal level that is proportional to the departure in length of time, ofsuch durations, or spacings, from the reference time period. Byproviding a detector unit responsive to a predetermined level of thetime integral signal, modulation of the pulse train may be so maintainedthat the circuit output (and the time integral signal) is always keptdesirously at zero.

In adapting the circuit of the invention for use as a monitor for therate of thread consumption of an industrial sewing machine, thefollowing factors obtain: A broken needle thread causes the sewingmachine consumption rate thereof to cease, whereas a broken bobbinthread causes the consumption'rate of the needle thread to decrease. Byproviding a pulley having spokes that are substantially equisized withthe spacings therebetween, and by directing a thin steady stream of airperpendicular to and at such spokes, a pulse train as required of airpressure pulses is had if the pulley is rotated by means of theconsumable thread, and if the pulley is of sufficient mass to filter theperiodic demand for thread by the sewing machine. A high rate of needlethread consumption eifects pulse durations and spacings that areminimal; a low rate of needle thread consumption effects pulse durationsand spacings that are substantial. Hence,

' by adapting the circuit of the invention to provide an output the timeintegral of which is zero only when the pulley rotational speed isrepresentative of a sewing machine that is functioning properly andconsuming needle thread at a 'normal or reference rate, then monitoringof the operation of such sewing machine, and of its thread consumption,is attained.

For ease in understanding the full scope of the invention, thefollowing'description is directed first to a specific form thereof thatis both in the presently preferred sewing machine environment, and alsoemploys fluid logic comice ponents, after which time the broader aspectsof the invention are described with relation to a logic circuit that isBoolean in nature.

A principal object of the invention is to provide a circuit for use inso controlling the modulation of a pulse train that the durations andspacings of the pulses thereof are timewise both substantially equal toa reference time period.

Another object of the invention is to provide a logical arrangement ofelements responsive to produce a control output signal when thedurations and spacings of pulses in a received pulse train are not, inlength of time, the same substantially as a reference time period.

Another object of the invention is to provide a fluid logic circuitresponsive to produce a control output signal when the durations andspacings of pulses in a received train of fluid pulses are not, inlength of time, the same substantially as a reference time period.

Another object of the invention is to provide a logic circuit for use inmonitoring the rotary speed of an element.

Another object of the invention is to provide apparatus for use inmonitoring thread consumption by a sewing machine or similarinstrumentality.

Another object of the invention is to provide apparatus for use inmonitoring the condition of two threads of a sewing machine by sensingthe consumption of only one of said threads.

The invention will be described with reference to the figures wherein:

FIG. 1 is a schematic diagram, partially in block form, of a presentlypreferred embodiment of the invention,

FIGS. 2A, 2B and 2C are signal diagrams useful in describing theoperation of the circuit depicted in FIG. 1,

FIG. 3, is a diagram of an operational curve for the presently preferredembodiment of the invention, and

FIG. 4 is a Boolean logic diagram useful in depicting the broaderaspects of the invention.

Referring to FIG. 1, a sewing machine 10 supports a journal 12 on whicha pulley 14 is rotatably supported. The pulley 14 is provided with aplurality of spokes 16; and needle thread 18 from the sewing machine 10winds on and drives the pulley 14. To prevent slipping of the thread 18on the pulley, at least a full turn of thread 18 is placed on it, and toguide the thread 18 onto the pulley, thread guides 20, 22 are employed.Ideally, the pulley spokes 16 are all substantially identical and ofgenerally the same configuration as any one spacing 24 between adjacentspokes, the number of spokes in the pulley being directly determinativeof the fineness of the control provided by the instant circuit. As apractical matter, however, the dimensions of the spokes, if desired, maybe sized difierently with respect to the spacings 24, with attendantly aproportional decrease in the fineness of the control obtained.

A transmitting tube 26 directs a steady stream of air, provided by asource 28, at the pulley spokes 16 (or spaces 24); and a receiving tube30 is specially aligned to receive the transmitted air stream when thepulley 14 is so rotated that the transmitting tube 26 aligns with apulley space 24. The transmitting and receiving tubes 26, 30 ideally areso sized that the transmitted air stream is substantially blocked fromthe receiving tube whenever the pulley rotation is such that a spokealigns with the air stream; and the needle thread 18 is disposed on thepulley 14 so as not to interfere with such air stream. Therefore, whenthe pulley 14 is stationary either a steady air stream, or no airstream, is directed to the receiving tube 30 depending respectively onwhether a space 24 or a spoke 16 aligns with the output of thetransmitting tube 26; when the pulley rotates, a train of air pulses isreceived by the receiving tube 30, and the pulses in such train havedurations and spacings as required, i.e. they are timewise substantiallyequal.

The output of the receiving tube 30, whether a steady air stream or not,or whether a train of air pulses, is applied to the control input 32 ofa turbulence-type fluid amplifier 34. The intake 36 of the amplifier 34is adapted to be continuously excited by a pressure supply 38, and theoutput (at 39) of the amplifier 34 is applied through a delay device 40to the control input 42 of a second turbulence amplifier 44. Inaddition, the output of the receiving tube 30 is applied to the controlinput 42 of the amplifier 44. The delay device 40, which may take theform of an appropriately cut length of tubing, provides a time delayequal to the duration of an air pulse as provid ed when the sewingmachine 10 is consuming thread at a normal, or reference, rate.(Obviously the delay may bemade adjustable to accommodate differentnormal rates ofthread consumption for different sewing machines and/ orconditions.)

The intake 46 of the amplifier 44 is excited by the pressure supply 38,and its output (at 48) is applied both directly to the control input 50of a third turbulence amplifier 52, and to the control input 50 of suchamplifier via a delay device 54. The delay device 54 which also providesa time delay equal to the duration of a reference pulse, may beidentical in form to the delay device 4%. The intake 56 of the amplifier52 is continuously excited by the pressure source 38, and the output (at58) of the amplifier 52- is applied to a pressure integrating element60, e.g. a diaphragm actuator, the output of which controls a detectorelement 62, which may for example be a microswitch that excites an alarmsystem.

As to operation of the circuit of FIG. 1 for monitoring the consumptionof thread by a sewing machine,.the description below relates tooperations under the following conditions: (1) The pulley 14 isstationary, as for example when the sewing machine needle thread 18 hasbroken, and a steady stream of air is transmitted to the receiving tube30 via a pulley space 24. (2) The pulley 14 is stationary, and no airstream reaches the receiving,

tube, as for example when a pulley spoke 16 blocks the air stream. (3)The sewing machine is so functioning normally that, the air pulsesproduced by means of the pulley are of the desired reference duration.(4) The produced air pulses are of longer duration than the referenceduration, as for example when the pulley is rotating at too low a. ratein response to, say, a broken bobbin thread. (5) When the pulley isrotating at too high a rateand the produced air pulses are of too shorta duration.

Condition 1.--A. steady air stream from the receiving tube. 30,, whileswitching the amplifier 34 so that it has no output, also causes theamplifier 44 to switch and produce no output. Without a pressure signalfrom the amplifier 44 from the receiving tube 30 to the control input 32of the.

amplifier 34 such amplifier does not switch and therefore produces asteady air stream output signal that flows fromthe pressure supply 38through the delay device 40 to the control input 42 of the amplifier 44,whereby such amplifier switches and thereby produces no output signal.

With no pressure signal from the amplifier 44 being applied to thecontrol input 50, of the amplifier 52, the amplifier 52 does not switchand, as, above, allows a steady air stream to flow from the supply 38.tothe integrator 60 for driving the detector62.

Condition 3.-See FIG. 2A which shows signal waveforms a through 1 asthey appear singularly, and in certain combinations thereof, atsimilarly noted points on.

FIG. 1. With a signal a. in. air pulses ha g urati ns equal timewise tothe reference time delays of the delay devices 40, 52 being applied tothe control input 32 of the amplifier 34, the amplifier 34 effectivelyinverts its applied signal to produce signal b, after which time thedelay device 40 brings the signal b, now as signal c, again into phasewith the signal a. With both signals a and c in phase and applied to theamplifier'44 control input 42 as a combined signal (a-l-c), an invertedform thereof, signal d, is produced. Since the signal d, is delayed bythe duration of a single reference pulse to produce the signal e, thecombination of the signals d and e is a steady pressure signal (d+e),which when applied to the input 50 of the amplifier 52 causes suchamplifier to cease producing an output. Hence, the integrator 60 alsoproduces no output signal when the rate of thread consumption is at thereference rate, and attendantly the detector 62 is not actuated.

Condition 4.-See FIG. 2B which shows a series of signal waveformssimilar to those shown in FIG. 2A, but indicating that the air pulsesproduced by a slowly rotating pulley are of longer duration than thoseproduced when the pulley is rotating at its reference rate. With thelong duration pulses of signal a applied to switch the amplifier 34 offand on, the signal b (an inverted signal a) is produced. Since the timedelay to the signal b, as provided by the delay device 40, is equal tothe reference pulse duration, the signal c applied to the control input42 of the amplifier 44 is not in phase with the signal a (as was thecase in FIG. 2A). Therefore the combined waveform signal (n+0) has airpulsesof still longer duration than those produced by the pulley, andattendantly the output of the amplifier 44 is a series of relativelywidely spaced pulses (signal d). Delaying such widely spaced pulses ofsignal d by the reference duration produces the waveform signal e, andcombining the signals d and e at the control input 50 of the amplifier52 causes such amplifier to switch periodically, thereby producing. apulse output signal (whereas when thread is consumed at its referencerate as depicted in FIG. 2A, the output signal f of the amplifier 52 isa steady state zero pressure signal). Integrating such amplifier 52output pulses by means for example of a diaphragm actuator produces asteady state pressure signal which, if above a predetermined thresholdlevel, effects actuation ofthe detector 616111611262.

Condition 5.In the case where the pulley 14 is rotating at too high aspeed, and the pulses produced thereby. are of relatively short durationas compared to pulses produced when the pulley rotates at its referencespeed (see signal-a of FIG. 2C), the amplifier 34 is turned off and onat a high rate, and thereby produces a high frequency pulse train b(inverted with respect to the signal pulse train a as produced by thepulley 14). The delay to the signal pulse train b provided by the delaydevice 40 causes-the pulse train signals a and c to be out of phase,whereby their combination at the control input 42 of the amplifier 44effects a pulse train (signal d) of shorter duration pulses than arebeing produced by the pulley. Delaying theseshort duration pulsesbymeans of the delay device 54- to produce the pulse train signal e, andcombining the pulse train signals d' and e to switch periodically. theamplifier 52 off and on has the effect of causing such amplifier to havean output pulse train signal f. Integrating the pulsed output signal 1by means of a diaphragm actuator results in a steady state pressurelevel,

which if above a predetermined threshold level effectsv of FIG, 1 thatthe integrator 60 connects to the exhaust output of the amplifier 52:and the operation of. the integrator 60 is reversed, whereby the FIG. 3curve will appear inverted.

As above noted the switching portion of the fluid control circuit ofFIG. 1 is essentially a special form of Boolean logic circuit, whichnaturally may take a variety of other forms. See FIG. 4 which indicatesthe logical functions performed by the FIG. 1 switching elements, andemploys primed notations thereon for those components having relatedparts in FIG. 1. The FIG. 1 amplifier 34, by inverting its receivedcontrol signal, provides a NOT function. So too, the FIG. 1 amplifier 44by switching in response to either the signal a or the signal c providesan OR function (element 44,), and since it inverts both of these signalsit also provides a NOT function, i.e. the OR-NOT functions of the logicdiagram components 44,, and 44,, together provide the NOR switchingfunction of the FIG. 1 fluid amplifier 44. Similarly, the amplifier 52by switching in response to either the signal d or the signal e providesan OR function (element 52 and by inverting both of these input controlsignals also provides a NOT function (element 52 i.e. the NOR functionof the FIG. 1 switching fluid amplifier 52 is provided by the logicdiagram components 52,, and 52 Integrating and detecting elements aredeliberately omitted from FIG. 3 since these components serve no part ofthe logic circuit.

While the invention has been described in its preferred embodiments, itis to be realized that the words which have been used are words ofdescription rather than of limitation, and that changes within thepurview of the appended claims may be made without departing from thetrue scope and spirit of the invention. That is, other embodiments ofthe invention may be had so long as the following functional stepsthereof are followed: (a) apply a signal modulated substantially asrequired by the invention to two parallel channels, (b) invert thesignal in one of the two channels, (c) delay the signal in one of thetwo channels by the duration of substantially one pulse width, (d)logically sum the signals so operated on, and then invert the logicalsum signal, (e) apply the logical sum signal to two parallel channels,(f) delay the signal in one of last named channels by substantially theduration of one pulse width, and (g) logically sum the delayed and theunoperated on sum signal to produce a new sum signal, and invert or notthe new logical sum signal depending on the output function desired.

Having thus set forth the nature of the invention, what is claimedherein is:

1. Circuit apparatus for use in controlling the modulation of a train ofpulses comprising a first pair of signal translating channels connectedin parallel and adapted to receive said pulse train, one of saidchannels being provided with a first NOT logic element, and also one ofsaid channels being provided with means for delaying its respectivesignal by substantially the duration of a reference time period, a firstOR logic element adapted to receive the output signals from both saidchannels to produce a logical sum signal, a second NOT logic elementadapted to receive the output logical sum signal from said first ORlogic element, a second pair of channels connected in parallel andadapted to receive the output signal from said second NOT element, andone of said second pair of channels being provided with means fordelaying its signal by a duration substantially the same as saidreference time period, and a second OR logic element adapted to receivethe signals from both channels of said second pair of channels forproducing a second logical sum signal.

2. The apparatus of claim 1 including a third NOT logical elementadapted to receive the output of said second OR logical element.

3. The apparatus of claim 2 wherein said pulse train is in the nature ofair pulses, wherein said first NOT element is a fluid amplifier thecontrol input of which is adapted to be excited by said pulse train,wherein said first OR element and said second NOT element togethercomprise a second fluid amplifier the control input of which is adaptedto receive the outputs of said first pair of channels, and wherein saidsecond OR logic element and said third NOT logic element togethercomprise a third fluid amplifier the control input of which is adaptedto receive the outputs of said second pair of parallel channels.

4. The apparatus of claim 3 including means adapted to receive theoutput of said third fluid amplifier for producing a pressure signalproportional to the time integral of such output, and actuable meansresponsive to a predetermined level of said time integral pressuresignal.

5. The apparatus of claim 4 wherein both said means for delaying signalsare substantially equisized lengths of tubing so cut that air pulsesprovided respectively thereto traverse the lengths of tubing inapproximately the reference time period.

6. The apparatus of claim 3 wherein both said means for delaying signalsare substantially equisized lengths of tubing so cut that air pulsesapplied respectively thereto traverse the lengths of tubing inapproximately the reference time period.

7. A fluid logic control circuit comprising means for producing a trainof pressure pulses, a first turbulence amplifier the control input ofwhich is adapted to receive said train of pulses, means for delayingpressure pulses by a reference amount of time, said last named meansbeing adapted to receive the output of said first turbulence amplifier,a second turbulence amplifier adapted to receive at its control inputboth the output of said means for producing said train of pressurepulses and the output of said means for delaying pulses, second meansfor delaying pulses by substantially said reference amount adapted toreceive the output of said second turbulence amplifier, and a thirdturbulence amplifier adapted to receive at its control input both theoutput of said second means for delaying pulses and the output of saidsecond turbulence amplifier.

8. The apparatus of claim 7 including a Wheel having a plurality ofspokes each of which is sized approximately the same as the spacingbetween any adjacent pair thereof, means for rotating said Wheel, meansfor directing a thin stream of air transverse to and by the spokes ofsaid wheel depending on the rotational phase of said wheel, and meansfor receiving the air which passes said wheel and applying it to saidfirst turbulence amplifier.

9. The apparatus of claim 8 wherein said spoked Wheel is a pulley, andwherein said apparatus includes thread handling means, the threadthereof being passed around said pulley for driving same, whereby airpulses are applied to said air receiving means at a rate proportional tothe rate at which said pulley rotates.

10. The apparatus of claim 9 wherein said thread handling means is asewing machine wherein the thread passed around said pulley is theneedle thread of said machine, and wherein both said means for delayingpressure pulses provide pulse delays substantially equal timewise to theduration of a pulse as generated when said pulley is rotated by threadbeing consumed at the normal sewing rate for said machine.

11. The apparatus of claim 10 including actuable means responsive to apredetermined level of the pressure level signal for warning of threadfailure and the like.

References Cited UNITED STATES PATENTS 3,191,860 6/1965 Wadey 13781.5 X3,226,570 12/1965 Rosenbann 307-88.5 3,275,015 9/1966 Meier 13781.53,302,398 2/1967 Taplin et al. 137-815 PATRICK D. LAWSON, PrimaryExaminer. H. H. HUNTER, Assistant Examiner.

1. CIRCUIT APPARATUS FOR USE IN CONTROLLING THE MODULATION OF A TRAIN OFPULSES COMPRISING A FIRST PAIR OF SIGNAL TRANSLATING CHANNELS CONNECTEDIN PARALLEL AND ADAPTED TO RECEIVE SAID PULSE TRAIN, ONE OF SAIDCHANNELS BEING PROVIDED WITH A FIRST NOT LOGIC ELEMENT, AND ALSO ONE OFSAID CHANNELS BEING PROVIDED WITH MEANS FOR DELAYING ITS RESPECITIVESIGNAL BY SUBSTANTIALLY THE DURATION OF A REFERENCE TIME PERIOD, A FIRSTOR LOGIC ELEMENT ADAPTED TO RECEIVE THE OUTPUT SIGNALS FROM BOTHCHANNELS TO PRODUCE A LOGICAL SUM SIGNAL, A SECOND NOT LOGIC ELEMENTADAPTED TO RECIEVE THE OUTPUT LOGICAL SUM SIGNAL FROM SAID FIRST ORLOGIC ELEMENT, A SECOND PAIR OF CHANNELS CONNECTED IN PARALLEL ANDADAPTED TO RECEIVE THE OUTPUT SIGNAL FROM SAID SECOND NOT ELEMENT, ANDONE OF SAID SECOND PAIR OF CHANNELS BEING PROVIDED WITH MEANS FORDELAYING ITS SIGNAL BY A DURATION SUBSTANTIALLY THE SAME AS SAIDREFERENCE TIME PERIOD, AND A SECOND OR LOGIC ELEMENT ADAPTED TO RECEIVETHE SIGNALS FROM BOTH CHANNELS OF SAID SECOND PAIR OF CHANNELS FORPRODUCING A SECOND LOGICAL SUM SIGNAL.